U.S. patent number 7,294,731 [Application Number 11/467,612] was granted by the patent office on 2007-11-13 for perfluoropolyether silanes and use thereof.
This patent grant is currently assigned to 3M Innovative Properties Company. Invention is credited to Wayne W. Fan, Richard M. Flynn.
United States Patent |
7,294,731 |
Flynn , et al. |
November 13, 2007 |
**Please see images for:
( Certificate of Correction ) ** |
Perfluoropolyether silanes and use thereof
Abstract
The present invention provides novel perfluoropolyether silanes,
compositions containing the novel perfluoropolyether silanes and
method of treating substrates, in particular substrates having a
hard surface such as ceramics or glass, to render them water, oil,
stain, and/or dirt repellent.
Inventors: |
Flynn; Richard M. (Mahtomedi,
MN), Fan; Wayne W. (Cottage Grove, MN) |
Assignee: |
3M Innovative Properties
Company (St. Paul, MN)
|
Family
ID: |
38658047 |
Appl.
No.: |
11/467,612 |
Filed: |
August 28, 2006 |
Current U.S.
Class: |
556/427 |
Current CPC
Class: |
C07F
7/1804 (20130101) |
Current International
Class: |
C07F
7/04 (20060101); C07F 7/08 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 789 050 |
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Aug 1997 |
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EP |
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0 797 111 |
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Sep 1997 |
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EP |
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WO 99/37720 |
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Jul 1999 |
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WO |
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WO 02/30848 |
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Apr 2002 |
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WO |
|
Other References
Essilor International, Ophthalmic Optics Files, "Materials", pp.
1-29 (Mar. 1997). cited by other .
Essilor International, Ophthalmic Optics Files, "Coatings", pp.
1-36 (Apr. 1997). cited by other .
Howell, J. L., et al., The preparation of primary
poly-hexafluoropropylene oxide halides (poly-HFRP-CF.sub.2X where
X=I, Br, Cl and F), J. Fluorine Chem., vol. 125, (2004), pp.
1513-1518. cited by other.
|
Primary Examiner: Richter; Johann
Assistant Examiner: Gale; Kellette
Attorney, Agent or Firm: Kokko; Kent S.
Claims
The invention claimed is:
1. A perfluoropolyether silane of the formula:
R.sub.f[--R.sup.1--C.sub.2H.sub.4--S--R.sup.2--Si(Y).sub.x(R.sup.3).sub.3-
-x].sub.y, wherein R.sub.f is a mono- or divalent
perfluoropolyether group, R.sup.1 is a covalent bond, --O--, or a
divalent alkylene or arylene group, or combinations thereof, said
alkylene groups optionally containing one or more catenary oxygen
atoms; R.sup.2 is a divalent alkylene or arylene group, or
combinations thereof, said alkylene groups optionally containing
one or more catenary oxygen atoms; Y is a hydrolysable group, and
R.sup.3 is a monovalent alkyl or aryl group, x is 1, 2 or 3; and y
is 1 or 2.
2. The perfluoropolyether silane of claim 1 wherein R.sub.f is a
perfluoropolyether group comprising perfluorinated repeating units
selected from the group consisting of --(C.sub.nF.sub.2n)--,
--(C.sub.nF.sub.2nO)--, --(CF(Z)O)--, --(CF(Z)C.sub.nF.sub.2nO)--,
--(C.sub.nF.sub.2nCF(Z)O)--, --(CF.sub.2CF(Z)O)--, and combinations
thereof, wherein n is 1 to 4 and Z is a perfluoroalkyl group, a
perfluoroalkoxy group, or perfluoroether group.
3. The perfluoropolyether silane of claim 1, wherein Y is a
halogen, a C.sub.1-C.sub.4 alkoxy group, or a C.sub.1-C.sub.4
acyloxy group.
4. The perfluoropolyether silane of claim 1 wherein said
perfluoropolyether moiety has a molecular weight of at least 750
g/mole.
5. The perfluoropolyether silane of claim 1 wherein said
perfluoropolyether moiety is selected from
--CF.sub.2O(CF.sub.2O).sub.m(C.sub.2F.sub.4O).sub.pCF.sub.2--,
wherein an average value for m and p is 0 to 50, with the proviso
that m and p are not simultaneously 0;
--CF.sub.2O(C.sub.2F.sub.4O).sub.pCF.sub.2--,
--CF(CF.sub.3)O--(CF.sub.2CF(CF.sub.3)O).sub.p--C.sub.4F.sub.8O--(CF(CF.s-
ub.3)CF.sub.2O).sub.p--CF(CF.sub.3)--, and
--(CF.sub.2).sub.3O(C.sub.4F.sub.8O).sub.p(CF.sub.2).sub.3--,
wherein an average value for p is 1 to 50.
6. The perfluoropolyether silane of claim 1 wherein R.sub.f is a
monovalent perfluoropolyether group.
7. The perfluoropolyether silane of claim 1 selected from the group
consisting of
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2OC.sub.3H-
.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2OC.sub.3H-
.sub.6SC.sub.3H.sub.6Si(OC.sub.2H.sub.5).sub.2
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CO.sub.2C.sub.3H.-
sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CO.sub.2C.sub.3H.-
sub.6SC.sub.3H.sub.6Si(OC.sub.2H.sub.5).sub.3
(CH.sub.3O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF.sub.2(OC.sub.-
2F.sub.4).sub.n(OCF.sub.2).sub.nCF.sub.2CH.sub.2OC.sub.3H.sub.6SC.sub.3H.s-
ub.6Si(OCH.sub.3).sub.3
(C.sub.2H.sub.5O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF.sub.2(O-
C.sub.2F.sub.4).sub.n(OCF.sub.2).sub.nCF.sub.2CH.sub.2OC.sub.3H.sub.6SC.su-
b.3H.sub.6Si(OC.sub.2H.sub.5).sub.3
(CH.sub.3O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF(CF.sub.3)[OCF-
.sub.2CF(CF.sub.3)].sub.nOC.sub.4F.sub.9O[(CF(CF.sub.3)CF.sub.2O].sub.mCF(-
CF.sub.3)CH.sub.2OC.sub.3H.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
(C.sub.2H.sub.5O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF(CF.sub.-
3)[OCF.sub.2CF(CF.sub.3)].sub.nOC.sub.4F.sub.9O[(CF(CF.sub.3)CF.sub.2O].su-
b.mCF(CF.sub.3)CH.sub.2OC.sub.3H.sub.6SC.sub.3H.sub.6Si(OC.sub.2H.sub.5).s-
ub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2CH.s-
ub.2SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2CH.sub.2S-
C.sub.3H.sub.6Si(OC.sub.2H.sub.5).sub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CF.sub.2OC.sub.3H-
.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
C.sub.3F.sub.7O[CF.sub.2CF.sub.2CF.sub.2O].sub.nC.sub.2F.sub.4CH.sub.2OC.-
sub.3H.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3, and
C.sub.3F.sub.7O[CF.sub.2CF.sub.2CF.sub.2O].sub.nC.sub.2F.sub.4CH.sub.2CH.-
sub.2SC.sub.3H.sub.6Si(OCH.sub.3).sub.3, wherein n is from 1 to 50
and n+m is up to 30.
8. A method of preparing the perfluoropolyether silane of claim 1
comprising the free radical addition of a mercaptosilane of the
formula HS--R.sup.2--Si(Y).sub.x(R.sup.3).sub.3-x, to an
ethylenically unsaturated fluorinated compound of the formula:
R.sub.f[--(R.sup.1--CH.dbd.CH.sub.2].sub.y, wherein R.sub.f is a
mono- or divalent perfluoropolyether group, R.sup.1 is a covalent
bond, --O--, or a divalent alkylene or arylene group, or
combinations thereof, said alkylene groups optionally containing
one or more catenary oxygen atoms; R.sup.2 is a divalent alkylene
or arylene group, or combinations thereof, said alkylene groups
optionally containing one or more catenary oxygen atoms; R.sup.3 is
a monovalent alkyl or aryl group, said alkylene groups, optionally
containing one or more catenary oxygen atoms; Y is a hydrolysable
group, and x is 1, 2 or 3, and y is 1 or 2.
9. The method of claim 8 wherein the free radical initiator is
selected from inorganic and organic peroxides, hydroperoxides,
persulfates, azo compounds, and redox initiators.
10. A coated article comprising a substrate having a coating of the
perfluoropolyether silane of claim 1 on a surface thereof.
11. The coated article of claim 10 wherein the substrate is
selected from glass, ceramics, metal, stone, thermoplastic
polymers, paints, powder coatings, and wood.
12. The coated article of claim 10 wherein the substrate has a
siliceous surface.
13. The coating article of claim 10 wherein the substrate is an
antireflective article.
14. A coating composition comprising the perfluoropolyether silane
of claim 1, an organic solvent, optionally an organic or inorganic
acid, and optionally water.
15. A method of applying an antisoiling coating to a substrate, the
method comprising applying a coating composition comprising at
least one perfluoropolyether silane of claim 1 and an organic
solvent to at least a portion of a surface of the substrate.
16. The method of claim 15 wherein the step of applying is selected
from spray coating, knife coating, spin coating, dip coating,
meniscus coating, flow coating, and roll coating.
17. The method of claim 15 wherein said coating composition further
comprises water and an acid.
18. The method of claim 15 comprising the steps of applying the
coating composition comprising the perfluoropolyether silane of
claim 1, and an organic solvent, then contacting the coated
substrate with an aqueous acid.
19. The method of claim 15 comprising between 0.01 and 50 percent
by weight of the perfluoropolyether silane.
20. The method of claim 15 further comprising the step of heating
said coated substrate to temperatures of 40 to 300.degree. C.
Description
FIELD OF THE INVENTION
The present invention relates to novel perfluoropolyether silanes,
compositions containing the novel perfluoropolyether silanes and
method of treating substrates, in particular substrates having a
hard surface such as ceramics or glass, to render them water, oil,
stain, and/or dirt repellent. The present invention also relates to
compositions for use in such a method.
BACKGROUND OF THE INVENTION
The use of fluorinated silanes, i.e., silane compounds that have
one or more fluorinated groups for rendering substrates such as
glass and ceramics oil and water repellent are known. For example
U.S. Pat. No. 5,274,159 describes destructible fluorinated alkoxy
silane surfactants that can be applied from an aqueous solution. WO
02/30848 describes compositions comprising fluorinated polyether
silanes for rendering ceramics oil and water repellent.
EP 797111 discloses compositions of alkoxysilane compounds
containing perfluoropolyether groups to form antifouling layers on
optical components. Additionally, U.S. Pat. No. 6,200,884 discloses
compositions of perfluoropolyether-modified aminosilanes that cure
into films having improved water and oil repellency and anti-stain
properties.
EP 789050 discloses the use of fluorinated polyether silanes for
making composite film coatings. U.S. Pat. No. 3,646,085 teaches
fluorinated polyether silanes for rendering glass or metal surfaces
oil and water repellent. WO 99/37720 discloses fluorinated
polyether silanes for providing antisoiling coating to
antireflective surfaces on substrates such as glass or plastic.
U.S. Pat. No. 3,950,588 discloses the use of fluorinated polyether
silanes to render ceramic surfaces such as bathroom tiles or
cookware water and/or oil repellent.
SUMMARY OF THE INVENTION
The present invention provides novel perfluoropolyether silanes of
the formula:
R.sub.f[--R.sup.1--C.sub.2H.sub.4--S--R.sup.2--Si(Y).sub.x(R.sup-
.3).sub.3-x].sub.y, wherein R.sub.f is a mono- or divalent
perfluoropolyether group, R.sup.1 is a covalent bond, --O--, or a
divalent alkylene or arylene group, or combinations thereof, said
alkylene groups optionally containing one or more catenary oxygen
atoms; R.sup.2 is a divalent alkylene or arylene group, or
combinations thereof, said alkylene groups optionally containing
one or more catenary oxygen atoms; Y is a hydrolysable group, and
R.sup.3 is a monovalent alkyl or aryl group, x is 1, 2 or 3,
preferably 3, and y is 1 or 2.
Although many fluorinated silane compositions are known in the art
for treating substrates to render them oil and water repellent,
there continues to be a desire to provide further improved
compositions for the treatment of substrates, in particular
substrates having a hard surface such as ceramics, glass and stone,
in order to render them water and oil repellent and easy to
clean.
There is also a need for treating glass and plastic as a hard
surface, particularly in the ophthalmic field, in order to render
them antisoiling, i.e. stain, dirt, oil and/or water resistant.
Desirably, such compositions and methods employing them can yield
coatings that have improved properties. In particular, it would be
desirable to improve the durability of the coating, including an
improved abrasion resistance of the coating. Furthermore, improving
the ease of cleaning of such substrates while using less
detergents, water or manual labor, is not only a desire by the end
consumer, but has also a positive impact on the environment. The
compositions can conveniently be applied in an easy and safe way
and are compatible with existing manufacturing methods. Preferably,
the compositions will fit easily into the manufacturing processes
that are practiced to produce the substrates to be treated. The
compositions preferably also avoid the use of ecologically
objectionable components.
The present invention further provides a method for coating a
substrate, particularly a hard substrate, with the
perfluoropolyether silanes to provide an antisoiling coating
thereto. In one embodiment, the present invention provides a method
of depositing the perfluoropolyether silanes on a substrate
comprising vaporizing the perfluoropolyether silane and depositing
it onto a substrate, such as by vapor deposition techniques. In
another embodiment, the invention comprises a coating composition
comprising the perfluoropolyether silane and a solvent, whereby the
coating compositions are applied to substrates to impart an
antisoiling coating thereto.
DETAILED DESCRIPTION
The present invention provides novel perfluoropolyether silanes,
and substrates bearing a coating of the perfluoropolyether silanes.
The silanes are of the formula
R.sub.f[--R.sup.1--C.sub.2H.sub.4--S--R.sup.2--Si(Y).sub.x(R.sup.3).sub.3-
-x].sub.y, wherein R.sub.f is a mono- or divalent
perfluoropolyether group, R.sup.1 is a covalent bond, --O--, or a
divalent alkylene or arylene group, or combinations thereof, said
alkylene groups optionally containing one or more catenary
(in-chain) oxygen atoms; R.sup.2 is a divalent alkylene or arylene
groups, or combinations thereof, said alkylene groups optionally
containing one or more catenary oxygen atoms; Y is a hydrolysable
group, and R.sup.3 is a monovalent alkyl or aryl group, x is 1, 2
or 3, preferably 3, and y is 1 or 2.
R.sub.f represents a mono- or divalent perfluoropolyether group.
The perfluoropolyether group can include linear, branched, and/or
cyclic structures, and may be saturated or unsaturated. It is a
perfluorinated group, i.e., essentially all C--H bonds are replaced
by C--F bonds. Preferably, it includes perfluorinated repeating
units selected from the group of --(C.sub.nF.sub.2n)--,
--(C.sub.nF.sub.2nO)--, --(CF(Z))--, --(CF(Z)O)--,
--(CF(Z)C.sub.nF.sub.2nO)--, --(C.sub.nF.sub.2nCF(Z)O)--,
--(CF.sub.2CF(Z)O)--, and combinations thereof. In these repeating
units Z is a perfluoroalkyl group, a perfluoroalkoxy group, or
perfluoroether group, all of which can be linear, branched, or
cyclic, and preferably have about 1 to about 9 carbon atoms and 0
to about 4 oxygen atoms. "n" is at least 1, and preferably 1 to 4.
Examples of perfluoropolyethers containing these repeating units
are disclosed in U.S. Pat. No. 5,306,758 (Pellerite).
For the monovalent perfluoropolyether group (wherein y is 1 in
formula (I) above), the terminal groups can be
(C.sub.nF.sub.2n+1)--, (C.sub.nF.sub.2n+1O)-- or
(X'C.sub.nF.sub.2nO)--, which may be linear or branched and wherein
X' is H, Cl, or Br, for example. Preferably, these terminal groups
are perfluorinated. In these repeating units or terminal groups, n
is 1 or more, and preferably 1 to 8. Preferred approximate average
structures for a divalent fluorinated polyether group include
--C.sub.4F.sub.8O--, C.sub.3--F.sub.6O--, --C.sub.5F.sub.10O--,
--C.sub.6F.sub.12O--,
--CF.sub.2O(CF.sub.2O).sub.m(C.sub.2F.sub.4O).sub.pCF.sub.2--,
wherein an average value for m and p is 0 to 50, with the proviso
that m and p are not simultaneously 0,
--CF.sub.2O(C.sub.2F.sub.4O).sub.pCF.sub.2--,
--CF(CF.sub.3)O--(CF.sub.2CF(CF.sub.3)O).sub.p--C.sub.4F.sub.8O--(CF(CF.s-
ub.3)CF.sub.2O).sub.p--CF(CF.sub.3)--, and
--(CF.sub.2).sub.3O(C.sub.4F.sub.8O).sub.p(CF.sub.2).sub.3--,
wherein an average value for each p is 1 to 50.
Of these, particularly preferred approximate average structures are
--CF.sub.2O(CF.sub.2O).sub.m(C.sub.2F.sub.4O).sub.pCF.sub.2--,
--CF.sub.2O(C.sub.2F.sub.4O).sub.pCF.sub.2--, and
--CF(CF.sub.3)O--(CF.sub.2CF(CF.sub.3)O).sub.p--C.sub.4F.sub.8O--(CF(CF.s-
ub.3)CF.sub.2O).sub.p--CF(CF.sub.3)--. Particularly preferred
approximate average structures for a monovalent perfluoropolyether
group include
C.sub.3F.sub.7O(CF(CF.sub.3)CF.sub.2O).sub.pCF(CF.sub.3)-- and
CF.sub.3O(C.sub.2F.sub.4O).sub.pCF.sub.2-- wherein an average value
for p is 1 to 50. As synthesized, these compounds typically include
a mixture of polymers.
The divalent R.sup.1 and R.sup.2 groups can independently include
linear, branched, or cyclic structures that may be saturated or
unsaturated, including alkylene, arylene and combinations thereof,
such as aralkylene and alkarylene. The R.sup.1 and R.sup.2 groups
can contain one or more catenary heteroatoms (e.g., oxygen,
nitrogen, or sulfur). The groups can also be substituted with
halogen atoms, preferably, fluorine atoms, although this is less
desirable, as this might lead to instability of the compound.
Preferably, the R.sup.1 and R.sup.2 groups are hydrocarbon groups,
preferably, linear hydrocarbon groups, optionally containing one or
more catenary heteroatoms. Examples of R.sup.1 and R.sup.2 groups
include alkylenes of the formula --(C.sub.mH.sub.2m)--, wherein m
is about 2 to about 20, and one or more non-adjacent --CH.sub.2--
groups are replaced by ether oxygen atoms, e.g.
--(C.sub.mH.sub.2m)--O--(C.sub.m'H.sub.2m')--, where m is 2 to 20,
m' is 0 to 20 and m+m' is 2 to 20.
Y represents a hydrolysable group in formula (I) such as for
example a halide, a C.sub.1-C.sub.4 alkoxy group, an acyloxy group
or a polyoxyalkylene group, such as polyoxyethylene groups as
disclosed in U.S. Pat. No. 5,274,159. By hydrolysable it is meant
the Y group will undergo an exchange reaction with water to form a
Si--OH moiety, which may further react to form siloxane groups.
Specific examples of hydrolysable groups include methoxy, ethoxy
and propoxy groups, chlorine and an acetoxy group.
R.sup.3 is a monovalent alkyl or aryl group and is generally
non-hydrolyzable.
Compounds of formula I suitable for compositions for treating
substrates of the present invention have a molecular weight (number
average) of at least about 200, and preferably, at least about
1000. Preferably, they are no greater than about 10000.
Examples of preferred perfluoropolyether silanes include, but are
not limited to, the following approximate average structures. The
number of repeat units n and m will vary, with n from 1 to 50,
generally 3 to 30, and n+m up to 30.
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2OC.sub.3H-
.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2OC.sub.3H-
.sub.6SC.sub.3H.sub.6Si(OC.sub.2H.sub.5).sub.2
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CO.sub.2C.sub.3H.-
sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CO.sub.2C.sub.3H.-
sub.6SC.sub.3H.sub.6Si(OC.sub.2H.sub.5).sub.3
(CH.sub.3O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF.sub.2(OC.sub.-
2F.sub.4).sub.n(OCF.sub.2).sub.nCF.sub.2CH.sub.2OC.sub.3H.sub.6SC.sub.3H.s-
ub.6Si(OCH.sub.3).sub.3
(C.sub.2H.sub.5O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF.sub.2(O-
C.sub.2F.sub.4).sub.n(OCF.sub.2).sub.nCF.sub.2CH.sub.2OC.sub.3H.sub.6SC.su-
b.3H.sub.6Si(OC.sub.2H.sub.5).sub.3
(CH.sub.3O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF(CF.sub.3)[OCF-
.sub.2CF(CF.sub.3)].sub.nOC.sub.4F.sub.9O[(CF(CF.sub.3)CF.sub.2O].sub.mCF(-
CF.sub.3)CH.sub.2OC.sub.3H.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
(C.sub.2H.sub.5O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF(CF.sub.-
3)[OCF.sub.2CF(CF.sub.3)].sub.nOC.sub.4F.sub.9O[(CF(CF.sub.3)CF.sub.2O].su-
b.mCF(CF.sub.3)CH.sub.2OC.sub.3H.sub.6SC.sub.3H.sub.6Si(OC.sub.2H.sub.5).s-
ub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2CH.s-
ub.2SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2CH.sub.2S-
C.sub.3H.sub.6Si(OC.sub.2H.sub.5).sub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CF.sub.2OC.sub.3H-
.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
C.sub.3F.sub.7O[CF.sub.2CF.sub.2CF.sub.2O].sub.nC.sub.2F.sub.4CH.sub.2OC.-
sub.3H.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3, and
C.sub.3F.sub.7O[CF.sub.2CF.sub.2CF.sub.2O].sub.nC.sub.2F.sub.4CH.sub.2CH.-
sub.2SC.sub.3H.sub.6Si(OCH.sub.3).sub.3.
The compounds of formula I can be synthesized using standard
techniques. For example, a commercially available, or readily
synthesized, mercaptosilane of the formula
HS--R.sup.2--Si(Y).sub.x(R.sup.3).sub.3-x, may be combined with an
ethylenically unsaturated perfluoropolyether compound of the
formula R.sub.f--R.sup.1--CH.dbd.CH.sub.2, as shown in the
following Scheme. Disilyl compounds of Formula I, where y is 2, may
also be prepared by these same general techniques.
##STR00001## where R.sup.1, R.sup.2, R.sup.3, R.sub.f, Y and x are
as previously defined for Formula I. With respect the addition
reaction of Scheme 1, the sulfur may add to either carbon atom of
the ethylenically unsaturated group in which case the
--C.sub.2H.sub.4-- group is of the structure --CH(CH.sub.3)-- or
--CH.sub.2CH.sub.2--.
The addition of the mercaptosilane (III) to the ethylenically
unsaturated compound (II) may be effected using free radical
initiators. Useful free radical initiators include inorganic and
organic peroxides, hydroperoxides, persulfates, azo compounds,
redox systems (e.g., a mixture of K.sub.2S.sub.2O.sub.8 and
Na.sub.2S.sub.2O.sub.5), and free radical photoinitiators such as
those described by K. K. Dietliker in Chemistry & Technology of
UV & EB Formulation for Coatings, Inks & Paints, Volume 3,
pages 276-298, SITA Technology Ltd., London (1991). Representative
examples include hydrogen peroxide, potassium persulfate, t-butyl
hydroperoxide, benzoyl peroxide, t-butyl perbenzoate, cumene
hydroperoxide, 2,2'-azobis(2-methylbutyronitrile), (VAZO 67) and
azobis(isobutyronitrile) (AIBN). The skilled artisan will recognize
that the choice of initiator will depend upon the particular
reaction conditions, e.g., choice of solvent.
Perfluoropolyether compounds having an ethylenically unsaturated
group, e.g. formula II, may be prepared by means known in the art.
For example, a perfluorinated dihydroalcohol of the general formula
R.sub.f--CH.sub.2--OH (prepared by reduction of the corresponding
perfluorinated acyl fluoride or ester), may be reacted with an
omega-haloalkene, such as allyl bromide.
##STR00002##
Alternatively, a perfluorinated acyl fluoride may be reacted by
fluoride ion catalyzed addition to an omega-haloalkene.
##STR00003##
Other ethylenically unsaturated perfluoropolyethers can be prepared
by the reaction of a perfluoropolyether iodide, by the reaction of
poly(hexafluoropropylene oxide) with lithium iodide at 180.degree.
C.) with ethylene using a free radical catalyst such as benzoyl
peroxide at 65.degree. C. in the absence of a solvent (described in
J. L. Howell et al., J. Fluorine Chem., vol. 125, (2004), p. 1513).
The obtained primary or secondary iodide can then undergo
dehydroiodination using, for example sodium methoxide in methanol,
to form the ethylenically unsaturated perfluoropolyether
precursor.
##STR00004##
Perfluoropolyether compounds can be obtained by oligomerization of
hexafluoropropylene oxide (HFPO) which results in a
perfluoropolyether carbonyl fluoride. This carbonyl fluoride may be
converted into an acid, acid salt, ester, amide or alcohol by
reactions well known to those skilled in the art. The carbonyl
fluoride or acid, ester or alcohol derived therefrom may then be
reacted further to introduce the desired groups according to known
procedures.
It will be evident to one skilled in the art that a mixture of
perfluoropolyethers according to formula (I) may be used to prepare
the fluorinated polyether compound of the fluorochemical
composition. Generally, the method of making the perfluoropolyether
according to formula (I) for the present invention will result in a
mixture of perfluoropolyethers that have different molecular
weights and are free of (1) fluorinated polyether compounds having
a perfluorinated polyether moiety having a molecular weight of less
than 750 g/mol and (2) fluorinated polyether compounds having a
perfluoropolyether moiety having a molecular weight greater than
10,000 g/mol.
The use of perfluoropolyethers corresponding to molecular weights
greater than about 10,000 g/mol can induce processing problems.
These problems are typically due to the fact that the higher
molecular weight materials lead to insolubility concerns, as well
as in difficulty in application methods such as CVD coating due to
the low vapor pressure of these higher molecular weight compounds.
Additionally, the presence of higher molecular weight fluorinated
polyether derivatives may have considerable impact on the
efficiency of the separation process of materials via
fractionation.
The fluorochemical composition are desirably free of or
substantially free of perfluoropolyether moieties having a
molecular weight of less than 750 g/mol and those moieties having a
molecular weight greater than 5000 g/mol. By the term
"substantially free of" is meant that the particular
perfluoropolyether moieties outside the molecular weight range are
present in amounts of not more than 10% by weight, preferably not
more than 5% by weight and based on the total weight of
perfluoropolyether moieties in the composition. Compositions that
are free of or substantially free of these moieties are preferred
because of their beneficial environmental properties and their
processability in the further reaction steps.
If it is desired to apply the compounds of Formula I by a vapor
deposition method, the molecular weight of the perfluoropolyether
moiety is preferably less than 10,000 g/mole, and more preferably
1000 to 5000 g/mole.
Coatings derived from the perfluoropolyether silane of formula I
may be applied to various substrates, particularly hard substrates,
to render them oil-, water-, and soil repellent. This coating can
be extremely thin, e.g. 1 to 50 molecular layers, though in
practice a useful coating may be thicker.
Although the inventors do not wish to be bound by theory, compounds
of the above formula I are believed to undergo a condensation
reaction with the substrate surface to form a siloxane layer via
hydrolysis or displacement of the hydrolysable "Y" groups of
Formula I. In this context, "siloxane" refers to --Si--O--Si--
bonds to which are attached R.sub.f segments (i.e.
perfluoropolyether segments as in Formula I herein), bonded to the
silicon atoms through organic linking groups (such as the R.sup.1
and R.sup.2 groups in formula I herein.
A coating prepared from the perfluoropolyether silane coating
composition that includes compounds of formula I includes the
perfluoropolyether silanes per se, as well as siloxane derivatives
resulting from bonding to the surface of a preselected substrate.
The coatings can also include unreacted or uncondensed "Si--Y"
groups. The composition may further contain may also contain
non-silane materials such as oligomeric perfluoropolyether
monohydrides, starting materials and perfluoropolyether alcohols
and esters. Likewise, vapor deposited perfluoropolyether silanes
may include the silanes of Formula I per se, as well as the
siloxane derivatives resulting from reaction with the substrate
surface.
In one embodiment, the invention provides a coating composition
comprising the perfluoropolyether silanol, a solvent, and
optionally water and an acid. To achieve good durability for many
substrates, such as ceramics, the compositions of the present
invention preferably include water. Thus the present invention
provides a method of coating comprising the steps of providing
contacting a substrate with a coating composition comprising the
perfluoropolyether silane of Formula I and a solvent. The coating
composition may further comprise water and an acid. In one
embodiment the method comprises contacting a substrate with a
coating composition comprising the silane of Formula I and a
solvent, and subsequently contacting the substrate with an aqueous
acid.
When present, the amount of water typically will be between 0.1 and
20% by weight, preferably between 0.5% by weight and 15% by weight,
more preferably between 1 and 10% by weight, relative to the weight
of the silane of Formula I.
In addition to water, the compositions of the invention may also
include an organic or inorganic acid. Organic acids include acetic
acid, citric acid, formic acid and the like; fluorinated organic
acids, such as CF.sub.3SO.sub.3H, C.sub.3F.sub.7CO.sub.2K or those
which can be represented by the formula
R.sub.f.sup.2[--(L).sub.a--Z].sub.b (IV) wherein R.sub.f.sup.2
represents a mono or divalent perfluoroalkyl or perfluoropolyether
group, L represents an organic divalent linking group, Z represents
an acid group, such as carboxylic, sulfonic or phosphonic acid
group; a is 0 or 1 and b is 1 or 2.
Examples of suitable R.sub.f.sup.2 groups include those given above
for R.sub.f. Examples of organic acids of formula (IV) include
C.sub.3F.sub.7O(CF(CF.sub.3)CF.sub.2).sub.10-30CF(CF.sub.3)COOH,
commercially available from DuPont or
CF.sub.3(CF.sub.2).sub.2OCF(CF.sub.3)COOH. Examples of inorganic
acids include sulphuric acid, hydrochloric acid and the like. The
acid will generally be included in the composition in an amount
between about 0.01 and 10%, more preferably between 0.05 and 5% by
weight, relative to the weight of the silane.
The acid may be formulated into the coating composition per se, or
subsequent to coating with the perfluoropolyether silane, the
coated substrate may be dipped in an acid solution to effect the
formation of a siloxane layer.
A coating composition of the present invention for many substrates
may include one or more organic solvents. The organic solvent or
blend of organic solvents used must be capable of dissolving at
least 0.01% by weight of the perfluoropolyether silane of formula
I. Furthermore, the solvent or mixture of solvents may have a
solubility for water of at least 0.1% by weight and a solubility
for acid of at least 0.01% by weight. If the organic solvent or
mixture of organic solvents do not meet these criteria, it may not
be possible to obtain a homogeneous mixture of the fluorinated
silane, solvent(s), and optional water and acid. Although such
non-homogeneous compositions could be used to treat a substrate,
the coating obtained therefrom will generally not have the desired
oil/water repellency and will not have sufficient durability
properties.
Suitable organic solvents, or mixtures of solvents can be selected
from alkanes, aromatic solvents; aliphatic alcohols, such as
methanol, ethanol, isopropyl alcohol; ketones, such as acetone or
methyl ethyl ketone; esters, such as ethyl acetate, methyl formate
and ethers, such as diisopropyl ether.
Fluorinated solvents may be used alone or in combination with the
organic solvents in order to improve solubility of the
perfluoropolyether silane. Such fluorinated solvents will generally
not be suitable for use on their own because may not meet the
requirements of solubility for water and acid, if present. Normally
the perfluoropolyether silane may be first coated from a
fluorinated solvent, and then subsequently contacted with aqueous
acid.
Examples of fluorinated solvents include fluorinated hydrocarbons,
such as perfluorohexane or perfluorooctane, available from 3M;
partially fluorinated hydrocarbons, such as pentafluorobutane,
available from Solvay, or CF.sub.3CFHCFHCF.sub.2CF.sub.3, available
from DuPont; hydrofluoroethers, including alkyl perfluoroalkyl
ether such as methyl perfluorobutyl ether or ethyl perfluorobutyl
ether, available from 3M as Novec.TM. HFE 7100 and Novec.TM. HFE
7200, respectively. Various blends of these materials with organic
solvents can be used.
A particularly preferred substrate is an antireflective substrate.
Antireflective (AR) surfaces are substrates prepared by vacuum
deposition or sputtering of metal oxide thin films on substrates
made of glass or plastic are useful in ophthalmic devices and
display devices of electronic equipment. Such metal oxide films are
relatively porous and consist of clusters of particles forming a
relatively rough profile. Such coatings help reduce glare and
reflection. When they are used in ophthalmic eyewear they reduce
eyestrain. When they are conductive coatings, they also help reduce
static discharge and electromagnetic emissions. Thus, one
application for these coatings is to provide contrast enhancement
and antireflective properties to improve the readability of display
devices, such as computer monitors. Antireflective substrates are
described in U.S. Pat. No. 5,851,674 incorporated by reference
herein in its entirety.
Various antisoiling coatings for antireflective coatings are known.
For example, U.S. Pat. No. 6,906,115 (Hanazawa et al.) and U.S.
Pat. No. 6,183,872 (Tanaka et al.) both describe silicon-containing
organic fluoropolymers that may be applied to antireflective
substrates, such as ophthalmic lenses. However, it has been noted
that such antisoiling coatings deleteriously effect the grinding
operations in ophthalmic lens manufacture. U.S. Pub. Appln. No
2003/004937, assigned to Essilor International, notes that the
adhesion at the interface pad/convex surface is altered or
compromised even for the most efficient hydrophobic and/or
oil-repellent coatings. The same reference attempts to overcome the
problems inherent with these commercial coatings by providing a
temporary protective coating having a surface energy of at least 15
mJoules/m.sup.2, so that the lens may be secured during the
grinding operations without slippage.
In many embodiments, the present invention further overcomes the
known deficiency of currently available coatings, in which
antireflective lenses may be coated with the perfluoropolyether
silane of the invention, and secured in the lens edge
cutting/grinding apparatus, thereby obviating the need for
temporary layers as described in U.S. Pub. Appln. No. 2003/0049370.
Thus, the present invention provides a method of edge cutting of
ophthalmic lenses by providing an ophthalmic lens having an
antireflective coating and a coating of the perfluoropolyether
silane of Formula I thereon, comprising blocking the lens, and edge
cutting the lens. The method may be done in the absence of a
temporary protective coating.
Sputtered metal oxide antireflective coatings are generally durable
and uniform. Also, their optical properties are controllable, which
makes them very desirable. They also have very high surface
energies and refractive indices. However, the high surface energy
of a sputtered metal oxide surface makes it prone to contamination
by organic impurities (such as skin oils). The presence of surface
contaminants results in a major degradation of antireflectivity
properties of the metal oxide coatings. Furthermore, because of the
high refractive indices, surface contamination becomes extremely
noticeable to the end-user.
The present invention provides an oil-, water-, and soil-repellent
coating on an antireflective surface that is relatively durable,
and more resistant to contamination, and overcomes the deficiencies
of prior art coatings with respect to edge-grinding processes. The
present invention provides in one embodiment a method and
composition for use in preparing an antireflective article
comprising a substrate having an antireflective surface and an
antisoiling coating of less than about 200 Angstroms thick
deposited thereon. The antisoiling coating comprises a
perfluoropolyether siloxane film of a thickness that does not
substantially change the antireflective characteristics of the
antireflective article.
The overall coating thickness of the antisoiling coating is
generally greater than a monolayer (which is typically greater than
about 15 Angstroms thick). That is, an antisoiling coating of the
present invention may be at least about 20 Angstroms thick, and
preferably, at least about 30 Angstroms thick. Generally, it is
less than about 200 Angstroms thick, and preferably, less than
about 100 Angstroms thick. The coating material is typically
present in an amount that does not substantially change the
antireflective characteristics of the antireflective article, i.e.
that the antireflectivity that is different by less than about 0.5
percentage units from that of the same article without the
perfluoropolyether silane coating.
The optical articles produced by the method of the present
invention include a substrate, such as glass or an organic
polymeric substrate, optionally having a primed surface on which is
coated an optional adhesion enhancing coating, an antireflective
composition, and an antisoiling coating derived from the
perfluoropolyether silane of formula I.
Suitable transparent substrates for antireflective articles include
glass and transparent thermoplastic materials such as
poly(meth)acrylate, polycarbonate, polythiourethanes, polystyrene,
styrene copolymers, such as acrylonitrile-butadiene-styrene
copolymer and acrylonitrile-styrene copolymer, cellulose esters,
particularly cellulose acetate and cellulose acetate-butyrate
copolymer, polyvinyl chloride, polyolefins, such as polyethylene
and polypropylene, polyimide, polyphenyleneoxide, and polyesters,
particularly polyethylene terephthalate. The term
"poly(meth)acrylate" (or "acrylic") includes materials commonly
referred to as cast acrylic sheeting, stretched acrylic,
poly(methylmethacrylate) "PPMA," poly(methacrylate),
poly(acrylate), poly(methylmethacrylate-co-ethylacrylate), and the
like. The substrate thickness can vary, however, for flexible
organic films it typically ranges from about 0.1 mm to about 1 mm.
Additionally, the organic polymeric substrate can be made by a
variety of different methods. For example, the thermoplastic
material can be extruded and then cut to the desired dimension. It
can be molded to form the desired shape and dimensions. Also, it
can be cell cast and subsequently heated and stretched to form the
organic polymeric substrate.
The substrate on which the antireflective coating is deposited may
include a primed surface. The primed surface can result from the
application of a chemical primer layer, such as an acrylic layer,
or from chemical etching, electronic beam irradiation, corona
treatment, plasma etching, or coextrusion of adhesion promoting
layers. Such primed substrates are commercially available. For
example, a polyethylene terephthalate substrate primed with an
aqueous acrylate latex is available from Imperial Chemical
Industries Films, Hopewell, N.C.
The substrate may also include an adhesion-enhancing coating to
improve adhesion between the antireflective coating and the
substrate. Such coatings are commercially available. The adhesion
enhancing coating is particularly desirable for use on flexible
organic polymeric substrates. In addition to enhancing adhesion of
the antireflective coating to a primed or unprimed organic
polymeric substrate, an adhesion enhancing coating may also provide
increased durability to an antireflective coating on a flexible
organic polymeric substrate by improving the scratch resistance of
the antireflective coating.
A wide variety of coating methods can be used to apply a
composition of the present invention to any substrate, such as
spray coating, knife coating, spin coating, dip coating, meniscus
coating, flow coating, roll coating, and the like. A preferred
coating method for application of a perfluoropolyether silane
mixture of the present invention includes spray application. A
substrate to be coated can typically be contacted with the coating
composition at room temperature (typically, about 20 to 25.degree.
C.).
The coating composition can be applied to substrates that are
preheated at a temperature of for example between 60 and
150.degree. C. This is of particular interest for industrial
production, where e.g. ceramic tiles can be treated immediately
after the baking oven at the end of the production line. Following
application, the treated substrate can be dried and cured at
ambient or elevated temperature, e.g. at 40 to 300.degree. C. and
for a time sufficient to dry. The process may also require a
polishing step to remove excess material.
Where the substrate is an antireflective coating, such as in
optical lenses, the perfluoropolyether silane may be deposited by
vapor deposition techniques, in addition to solution coating
techniques. The conditions under which the perfluoropolyether
silane is vaporized may vary according to the structure and
molecular weight of the antisoiling perfluoropolyether silane. In
some embodiments of the invention, the vaporizing may take place at
pressures less than about 0.01 torr, at pressures less than
10.sup.-4 torr or even 10.sup.-5 torr. In embodiments of the
invention, the vaporizing may take place at temperatures of at
least about 100.degree. C., or above 200.degree. C., or above
300.degree. C. Advantageously, it has been found that the instant
perfluoropolyether silanes may be vapor deposited at lower
temperatures than other antisoiling coatings, such as those
disclosed in U.S. Pat. No. 6,991,826 (Pellerite et al.).
The vapor deposition method may reduce opportunities for
contamination of the antireflective article surface through
additional handling and exposure to the environment, leading to
correspondingly lower yield losses. Furthermore, as the
antireflective coatings are generally applied by vapor deposition,
it is more efficient to apply the perfluoropolyether silanes by the
same process in the same vacuum chamber. Thus, the method of the
present invention enables application of the antisoiling
compositions to antireflective lenses under processing conditions
similar to those used in the industry for other applications, at
decreased capital equipment costs and with the necessity of solvent
usage eliminated.
In one embodiment, the vaporizing comprises placing the
perfluoropolyether silane and the antireflective substrate into a
chamber, decreasing the pressure in the chamber, and heating the
perfluoropolyether silane. The perfluoropolyether silane is
typically maintained in a crucible, but in some embodiments, the
silane is imbibed in a porous matrix, such as a ceramic pellet, and
the pellet heated in the vacuum chamber. In a preferred embodiment,
the antireflective substrate comprises an antireflective ophthalmic
lens. Furthermore, the antireflective ophthalmic lens may comprise
a polycarbonate resin and an antireflective coating on the surface
of the polycarbonate resin.
The present invention also provides a method of depositing an
perfluoropolyether silane on an antireflective-coated ophthalmic
lens comprising vaporizing an perfluoropolyether silane of Formula
I and depositing the perfluoropolyether silane onto an
antireflective coated ophthalmic lens, wherein the
perfluoropolyether silane is placed in a first chamber and the
antireflective coated ophthalmic lens is placed in a second chamber
connected to the first chamber such that vaporized
perfluoropolyether silane from the first chamber can deposit on the
antireflective coated ophthalmic lens in the second chamber. In
another aspect of the invention, the second chamber may remain at
ambient temperature while the first chamber is heated.
The present invention also provides a method for depositing the
perfluoropolyether silane onto an antireflective substrate that may
comprise placing the silane and the antireflective substrate into a
same chamber, heating the perfluoropolyether silane, and lowering
the pressure in the chamber. Under some conditions, with some
substrates, the antireflective substrate and the perfluoropolyether
silane may be heated to the same temperature.
In a further aspect, the present invention provides a method of
preparing an antireflective article comprising depositing an
antireflective layer onto the surface of a transparent substrate
and vapor depositing the perfluoropolyether silane of Formula I
onto the surface of the antireflective wherein the average
molecular weight of the perfluoropolyether moiety is about 750 to
about 5000, preferably 1000 to 3000 g/mole.
Other useful substrates include ceramics, glass, metal, natural and
man-made stone, thermoplastic materials (such as
poly(meth)acrylate, polycarbonate, polystyrene, styrene copolymers,
such as styrene acrylonitrile copolymers, polyesters, polyethylene
terephthalate), paints (such as those based on acrylic resins),
powder coatings, (such as polyurethane or hybrid powder coatings),
and wood. Various articles can be effectively treated with the
perfluoropolyether solution of the present invention to provide a
water and oil repellent coating thereon. Examples include ceramic
tiles, bathtubs or toilets, glass shower panels, construction
glass, various parts of a vehicle (such as the mirror or
windscreen), glass, and ceramic or enamel pottery materials.
Suitable substrates that can be treated in with the
perfluoropolyether silane coating composition include substrates
having a hard surface preferably with functional groups capable of
reacting with the perfluoropolyether silane according to Formula
(I). Preferably, such reactivity of the surface of the substrate is
provided by active hydrogen atoms. When such active hydrogen atoms
are not present, the substrate may first be treated in a plasma
containing oxygen or in a corona atmosphere to make it reactive to
the perfluoropolyether silane.
Useful substrates include those siliceous substrates including
ceramics, glazed ceramics, glass, concrete, mortar, grout and
natural and man-made stone. Various articles can be effectively
treated with the perfluoropolyether silane of the present invention
to provide a water and oil repellent coating thereon. Examples
include ceramic tiles, bathtubs or toilets, glass shower panels,
construction glass, various parts of a vehicle (such as the mirror
or windscreen), and ceramic or enamel pottery materials. Treatment
of glass employed for ophthalmic purposes, e.g., glass lenses, with
the composition of the present invention is especially
advantageous.
Treatment of the substrates results in rendering the treated
surfaces less retentive of soil and more readily cleanable due to
the oil and water repellent nature of the treated surfaces. These
desirable properties are maintained despite extended exposure or
use and repeated cleanings because of the high degree of durability
of the treated surface as can be obtained through the compositions
of this invention.
The substrate may be cleaned prior to applying the compositions of
the invention so as to obtain optimum characteristics, particularly
durability. That is, the surface of the substrate to be coated
should be substantially free of organic contamination prior to
coating. Cleaning techniques depend on the type of substrate and
include, for example, a solvent washing step with an organic
solvent, such as acetone or ethanol.
The coating composition is typically a relatively diluted solution,
containing between 0.01 and 50 percent by weight of the
perfluoropolyether silane, more preferably, between 0.03 and 3
percent by weight of the perfluoropolyether silane, and most
preferably, between 0.05 and 1.0 percent by weight of
perfluoropolyether silane. The ratio of the solvents, and optional
water and acid should be chosen so as to obtain a homogeneous
mixture.
For ease of manufacturing and for reasons of cost, the coating
compositions of the present invention will generally be prepared
shortly before use by diluting a concentrate of the
perfluoropolyether silane of formula (I). The concentrate will
generally comprises a concentrated solution of the
perfluoropolyether silane of formula (I) in an organic solvent
without water and/or acid being present in such concentrate. The
concentrate should be stable for several weeks, preferably at least
1 month, more preferably at least 3 months. It has been found that
the perfluoropolyether silane of formula (I) can be readily
dissolved in an organic solvent at high concentrations.
A wide variety of coating methods can be used to apply a
composition of the present invention, such as spray coating, knife
coating, spin coating, dip coating, meniscus coating, flow coating,
roll coating, and the like, in addition to the vapor deposition
techniques previously described. One coating method for application
of a perfluoropolyether silane coating composition is spray
application. Roll coating may comprise feeding the coating
composition to a doctor blade, transferring the coating composition
from the doctor blade to a gravure roll, and applying the coating
composition to the antireflective surface of the substrate from the
gravure roll. It may further comprise the step of coating the
antisoiling coating composition further comprises applying a soft
roll to a surface opposing the surface of the substrate.
A substrate to be coated can typically be contacted with the
coating composition at room temperature (typically, about 25 to
200.degree. C.). Alternatively, the mixture can be applied to
substrates which are preheated at a temperature of for example
between 60.degree. C. and 150.degree. C. This is of particular
interest for industrial production, where e.g. ceramic tiles can be
treated immediately after the baking oven at the end of the
production line. Following application, the treated substrate can
be dried and cured at ambient or elevated temperature, e.g. at 40
to 300.degree. C. and for a time sufficient to dry. The process may
also require a polishing step to remove excess material.
EXAMPLES
Objects and advantages of this invention are further illustrated by
the following examples, but the particular materials and amounts
thereof recited in these examples, as well as other conditions and
details, should not be construed to unduly limit this invention.
These examples are merely for illustrative purposes only and are
not meant to be limiting on the scope of the appended claims.
All parts, percentages, ratios, etc. in the examples and the rest
of the specification are by weight, unless noted otherwise.
Solvents and other reagents used were obtained from Sigma-Aldrich
Chemical Company, St. Louis, Mo. unless otherwise noted.
Test Methods
Nuclear Magnetic Resonance (NMR)
.sup.1H and .sup.19F NMR spectra were run on a Varian UNITY plus
400 Fourier transform NMR spectrometer (available from Varian NMR
Instruments, Palo Alto, Calif.).
Gas Chromatography/Mass Spectroscopy (GCMS)
GCMS samples were run on, for example, a Finnigan TSQ7000 mass
spectrometer (available from Thermo Electron Corporation, Waltham,
Mass.).
Gas Chromatography (GC)
GC samples were run on a Hewlett Packard 6890 Series Gas
Chromatograph, obtainable from Agilent Technologies, Palo Alto,
Calif.
IR Spectroscopy (IR)
IR spectra were run on a Thermo-Nicolet, Avatar 370 FTIR,
obtainable from Thermo Electron Corporation, Waltham, Mass.
Example 1
Preparation of
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2OC.sub.3H-
.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
The intermediate alcohol was prepared as follows: Isopropyl alcohol
(200 grams) was placed in a 2 L three-necked round bottom flask
equipped with an overhead stirrer, temperature sensor and addition
funnel and cooled to <10.degree. C. using a water/ice bath.
Sodium borohydride (34 grams, 0.9 mol) was added in several small
portions.
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CO.sub.2CH.sub.3
(900 grams, M.sub.n=1262, 0.71 mol) was added dropwise while
stirring under nitrogen. The temperature was maintained between
0.degree. C. and 10.degree. C. The ester addition was completed in
approximately one hour. After the addition of the ester was
complete, the reaction was continuously stirred while maintaining
the temperature between 0.degree. C. and 10.degree. C. The reaction
mixture was then allowed to warm to room temperature and stirred
overnight.
600 mL of a 20-wt % aqueous solution of ammonium chloride was added
dropwise to the thickened mixture at room temperature. On complete
addition, the temperature was kept below 45.degree. C. using a
cooling bath. After adding all of NH.sub.4Cl solution, the mixture
was stirred at room temperature for about 30 minutes, then the
phases were allowed to separate. The upper aqueous layer was
removed and the lower alcohol phase was washed three times with 500
mL portions of deionized water. The residual solvent was removed by
distillation under reduced pressure using rotary evaporator at
60.degree. C. to yield 884 grams of the intermediate (colorless
oil).
The intermediate ether was prepared as follows:
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2OH
(200 grams, M.sub.n=1234, 0.16 mol) was placed in a 2 L
three-necked round bottom flask equipped with a stirring bar,
temperature sensor and condenser. Tert-Butyl alcohol (400 grams)
was added, followed by potassium tert-butoxide (20 grams, 0.18
mol), added in small portions. The reaction mixture was heated to
40.degree. C. under nitrogen. The mixture, which was initially
cloudy, cleared to a transparent solution. Allyl bromide (21.6
grams, 0.18 mol) was added in one portion. The cloudy reaction
mixture was then heated to 40.degree. C. under nitrogen for 18
hours, then the reaction mixture containing undissolved salts was
cooled to room temperature and diluted with 500 mL deionized water
followed by 250 mL 2N HCl and 500 mL deionized water. The mixture
was stirred for 30 minutes and the layers were allowed to separate.
The aqueous phase was decanted. The organic phase was washed two
additional times with 1 L deionized water. 250 mL HFE-7100
(available under trademark Novec.TM. HFE-7100 Fluid, from 3M
Company, St. Paul, Minn.) was added to dissolve the product. The
organic phase was separated from remaining water in a separatory
funnel and the excess HFE-7100 removed under vacuum by rotary
evaporation at 60.degree. C. to yield 212 grams of a colorless oil
of the product allyl ether:
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2OCH.sub.2-
CH.dbd.CH.sub.2.
The product allyl ether, (24 grams, 0.019 mole, M.sub.n=1274,
consisting of a mixture of oligomeric compounds with the value of n
ranging from about 3 to about 8),
HSC.sub.3H.sub.6Si(OCH.sub.3).sub.3 (3.7 grams, 0.019 mol, obtained
from Alfa Aesar, Ward Hill, Mass.), ethyl acetate (60 g) and
2,2'-azobis(2-methylpropionitrile) (Vazo.TM. 64, 0.12 grams,
obtained from DuPont de Nemours & Co., Wilmington, Del.) were
combined in a 250 mL round bottom flask equipped with a
thermocouple temperature probe, magnetic stir bar and a water
filled condenser under a nitrogen atmosphere. The mixture was then
degassed four times, heated to reflux and held at that temperature
for 16 hours during which time the reaction solution became
completely homogeneous. The solution was cooled in a dry
ice/acetone bath which caused a phase separation. The upper ethyl
acetate phase was removed and the remaining lower phase extracted
with FC72.TM. (perfluorohexane, obtained from 3M Company, St. Paul,
Minn.), the lower fluorochemical phase separated from the residual
ethyl acetate and subsequently the FC72.TM. removed by rotary
evaporation. The IR spectrum (Thermo-Nicolet, Avatar 370 FTIR,
obtainable from Thermo Electron Corporation, Waltham, Mass.) was
consistent with the expected silane.
Example 2
Preparation of
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CO.sub.2C.sub.3H.-
sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.2
Hexafluoropropylene oxide was oligomerized to give an acid fluoride
mixture
(C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)COF)
essentially as described in U.S. Pat. No. 3,242,218 and
fractionated to remove lower boiling point oligomers as described
in U.S. Pat. No. 6,923,921. Allyl alcohol (12.8 grams, 0.22 mol)
was added to the acid fluoride mixture (87 grams, M.sub.n=1180) in
one portion and the mixture stirred at room temperature (after the
initial exotherm) for 18 hours. The reaction mixture was diluted
with acetone and the lower insoluble fluorochemical phase separated
and washed once more with an equal volume of acetone. Residual
acetone in the fluorochemical phase was removed by rotary
evaporation to give 81.1 grams oil. The IR spectrum showed the
carbonyl band for the allyl ester at 1787.4 cm.sup.-1. Analysis of
the mixture by GC (Hewlett Packard 6890 Series Gas Chromatograph,
obtainable from Agilent Technologies, Palo Alto, Calif.) showed
that the starting acid fluoride components were completely gone and
a new series of peaks for the allyl ester
(C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CO.sub.2CH.sub.2-
CH.dbd.CH.sub.2) had appeared. There was approximately 8% of a
series of oligomers in which the COF group was replaced by hydrogen
and this material was used without further purification in the next
step.
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CO.sub.2CH.sub.2C-
H.dbd.CH.sub.2 (50 grams, 0.041 mol),
HSC.sub.3H.sub.6Si(OCH.sub.3).sub.3 (9.6 grams, 0.049 mol, obtained
from Alfa Aesar, Ward Hill, Mass.), 2-butanone (60 grams) and
2,2'-azobis(2-methylpropionitrile) (Vazo.TM. 64, 0.16 grams,
obtained from DuPont de Nemours & Co., Wilmington, Del.) were
combined in a 250 mL round bottom flask equipped with a
thermocouple temperature probe, magnetic stir bar and a water
filled condenser under a nitrogen atmosphere. After degassing, the
mixture was heated to 79.degree. C. for 16 hours, and then cooled
to room temperature. FC72.TM. (about 50 mL) was added and the lower
phase separated and washed one time with acetone to remove the
excess mercaptosilane. The solvents were removed by rotary
evaporation to afford 50.1 grams of a light yellow oil. This
product was analyzed by H-NMR (Varian UNITY plus 400 Fourier
transform NMR spectrometer (available from Varian NMR Instruments,
Palo Alto, Calif.) and found to be a mixture of 45% ester/silane
and 40% starting material allyl ester with about 15% of the
corresponding hydride. The mixture was subsequently treated with 20
grams more of the mercaptosilane under identical reaction
conditions to those described above to afford the final composition
which was 81% desired silane, 0.6% starting allyl ester and 18%
hydride.
Example 3
Preparation of
(CH.sub.3O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF.sub.2(OC.sub.-
2F.sub.4)n(OCF.sub.2)nCF.sub.2CH.sub.2OC.sub.3H.sub.6SC.sub.3H.sub.6Si(OCH-
.sub.3).sub.3
Fomblin.TM. ZDOL perfluoropolyether diol (157 grams, EW=950,
obtained from Solvay Solexis, Houston, Tex.), was dissolved in a
mixture of HFE.TM. 7100 (150 mL) and dimethoxyethane (100 mL,
obtained from Sigma-Aldrich, St. Louis, Mo.) in a 1 L, 3-necked
round bottom flask equipped with a thermocouple, addition funnel
and overhead stirrer. To this mixture, potassium hydroxide (14.0
grams, dissolved in 9 mL water) was added and the mixture heated to
between 40.degree. C. and 50.degree. C. and stirred for one hour.
Tetrabutylammonium bromide (3.0 grams dissolved in 1 mL water) was
added followed by the dropwise addition of allyl bromide (31 grams,
obtained from Sigma-Aldrich, St. Louis, Mo.) over a period of about
one hour. The reaction mixture was then stirred for 16 hours at
45.degree. C. A distillation head was attached and the solvents and
water were distilled until the pot temperature reached about
120.degree. C. The reaction mixture was then cooled, a vacuum of
0.02 atmospheres (15 mmHg) applied, and the temperature was again
raised to about 120.degree. C. The mixture was held at this
temperature for about one hour. After cooling to room temperature,
HFE.TM. 7100 (250 mL) was added and the mixture was filtered under
vacuum through a sintered glass funnel to remove the solids. The
solids were washed with a further 75 mL of HFE.TM. 7100. The
filtrate was washed one time with 1% aqueous hydrochloric acid, the
lower fluorochemical phase separated and the solvent removed by
rotary evaporation to give 158 grams of amber, clear liquid of the
bis-allyl ether. The IR spectrum showed that the alcohol band had
completely disappeared.
The bis-allyl ether (35.8 grams, 0.017 mol),
HSC.sub.3H.sub.6Si(OCH.sub.3).sub.3 (13.5 grams, 0.067 mol), ethyl
acetate (100 grams) and 2,2'-azobis(2-methylpropionitrile)
(Vazo.TM. 64, 0.16 grams) were combined in a 250 mL round bottom
flask equipped with a thermocouple temperature probe, magnetic stir
bar and a water filled condenser under a nitrogen atmosphere. After
degassing as in Example 1, the mixture was heated to 70.degree. C.
for 16 hours. The solvent was removed by rotary evaporation and the
excess mercaptosilane starting material removed by vacuum
distillation at 0.002 atmospheres (2 mm Hg) to yield 39.6 grams of
the desired product.
Example 4
Preparation of
(CH.sub.3O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF(CF.sub.3)[OCF-
.sub.2CF(CF.sub.3)].sub.nOC.sub.4F.sub.9O[(CF(CF.sub.3)CF.sub.2O].sub.mCF(-
CF.sub.3)CH.sub.2OC.sub.3H.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
This silane was prepared as in Example 3, except with the following
charges: Fluorochemical diol, prepared as in U.S. Pat. No.
3,574,770, hydroxyl EW=610: 100 grams; HFE.TM. 7100: 150 mL;
dimethoxyethane: 100 mL; KOH: 14 grams dissolved in 9 mL water;
tetrabutylammonium bromide: 3 grams dissolved in 1 mL water; allyl
bromide: 31 grams (0.26 mol). The reaction conditions and the
workup procedure were identical to Example 3 to afford 92 grams of
tan liquid of the desired bis (allyl) ether.
The bis (allyl) ether (20 grams, 0.015 mol) was combined with
HSC.sub.3H.sub.6Si(OCH.sub.3).sub.3 (14 g, 0.07 mol), ethyl acetate
(40 grams) and 2,2'-azobis(2-methylpropionitrile) (Vazo.TM. 64,
0.045 grams) in a 250 mL round bottom flask equipped with a
thermocouple temperature probe, magnetic stir bar and a water
filled condenser under a nitrogen atmosphere. After degassing, the
mixture was heated to 70.degree. C. for 16 hours. The solvent was
removed by rotary evaporation and the excess mercaptosilane removed
by vacuum distillation at 0.002 atmospheres (2 mmHg) to yield 25.6
grams of the desired product. The IR spectrum was consistent with
the desired bis (silane).
Example 5
Preparation of
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2CH.sub.2S-
C.sub.3H.sub.6Si(OCH.sub.3).sub.3
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.dbd.CH.sub.2
was prepared by reaction of
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CH.sub.2CH.sub.2I
with sodium methoxide in methanol at reflux. The iodide in turn was
prepared by the reaction of
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)I with
ethylene at 65.degree. C. using benzoyl peroxide as initiator. The
vinyl compound (28.5 grams, 0.026 mol, about 76% purity) was
combined with HSC.sub.3H.sub.6Si(OCH.sub.3).sub.3 (10.2 grams, 0.05
mol), 2-butanone (about 60 grams) and
2,2'-azobis(2-methylpropionitrile) (Vazo.TM. 64, 0.1 grams) in a
250 mL round bottom flask equipped with a thermocouple temperature
probe, magnetic stir bar and a water filled condenser under a
nitrogen atmosphere. After degassing, the mixture was heated to
70.degree. C. for 16 hours. The solvent was removed by rotary
evaporation and the residue taken up in perfluoropentane, PF
5050.TM. (available as 3M.TM. Performance Fluid PF-5050 from 3M
Company, St. Paul, Minn.) and washed with 2-butanone to remove the
excess starting material silane and the solvent removed by rotary
evaporation to afford 30.5 grams silane.
Example 6
Preparation of
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O).sub.nCF(CF.sub.3)CF.sub.2OC.sub.3H-
.sub.6SC.sub.3H.sub.6Si(OCH.sub.3).sub.3
The intermediate
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CF.sub.2OCH.sub.2-
CH.dbd.CH.sub.2 was prepared as follows:
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)COF
(M.sub.n=1180, prepared as described in Example 2, 170 grams, 0.14
mol), anhydrous diglyme (354 grams), potassium iodide (0.5 grams),
potassium fluoride (12.8 grams, 0.22 mol), Adogen.TM. 464 (9.3
grams of a solution of 49% by weight in anhydrous diglyme) and
allyl bromide (54 grams, 0.44 mol) were combined in a 1L three
necked round bottom flask equipped with an overhead stirrer,
condenser and thermocouple temperature probe and the mixture heated
to 75.degree. C. with stirring under a nitrogen atmosphere for 72
hours. An additional 74 grams of allyl bromide was then added and
the mixture heated at 75.degree. C. for an additional 72 hours. The
composition of the reaction mixture at this time was about 44%
starting material acid fluoride, 41% desired allyl ether and 10%
allyl ester. The reaction mixture was filtered to remove the solids
and phase separated from the diglyme solution. The fluorochemical
phase was then washed with ethyl acetate to remove the remaining
organic solvents and reagents. Further purification was effected by
dilution of the fluorochemical phase with HFE.TM. 7100 followed by
reaction with aqueous potassium hydroxide to a phenolphthalein
endpoint. After phase separation (which was effected by freezing
the emulsified reaction mixture), the resulting fluorochemical
phase was distilled and the distillate used in the following
procedure. The composition of the distillate was approximately 34%
of the allyl ether and 57%
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCFHCF.sub.3.
The allyl ether prepared as described above was treated with
HSC.sub.3H.sub.6Si(OCH.sub.3).sub.3 (14.0 grams) in 2-butanone
solvent (125 mL) using AIBN initiator (0.15 g) and degassed. This
reaction mixture was heated to 70.degree. C. for 16 hours. After
cooling to room temperature, the reaction mixture was treated with
perfluoropentane to extract the product following by washing of the
perfluoropentane solution with 2-butanone to remove the excess
silane.
Treatments and Test Methods
Treatment of Ophthalmic Lenses by Dip Coat
A 0.1% solution of the selected fluorochemical silane in
HFE-7100.TM. was placed in a glass container of the dip coater. The
clean lens was dipped into the solution at the speed of 15 mm/sec
and allowed to stay submerged for 2 seconds. Then the lens was
withdrawn from the solution at the speed of 15 mm/sec. The coated
lens was dried for 30 minutes in air and then dipped into 0.1% HCl
solution at a similar dipping and withdrawal speed. Any excess acid
was blown off with nitrogen gas. The lens was placed in an aluminum
pan and cured in the oven for 30 minutes at 60.degree. C.
Treatment of Ophthalmic Lenses by Chemical Vapor Deposition
(CVD)
A clean lens was treated with each of selected fluorochemical
silanes of this invention as well as a comparative silane
(ECC-1000.TM., Easy Clean Coating-1000.TM.,
(CH.sub.3O).sub.3SiC.sub.3H.sub.6NHCOCF.sub.2(OC.sub.2F.sub.4)n(OCF.sub.2-
)nCF.sub.2CONHC.sub.3H.sub.6Si(OCH.sub.3).sub.3, obtained from 3M
Company, St. Paul, Minn.) in a vapor deposition chamber under
3.times.10.sup.-7 torr pressure. The vaporization temperature for
the silanes ranged from 350-500.degree. C. as indicated in Table 1
below.
The CVD (chemical vapor deposition) experimental results reported
in Table 1 show that the silanes of this invention, with the
mercapto linkage group, require lower vaporization temperatures for
effective deposition. For example, the CVD process temperature for
the silane of Example 3,
(CH.sub.3O).sub.3SiC.sub.3H.sub.6SC.sub.3H.sub.6OCH.sub.2CF.sub.2(OC.sub.-
2F.sub.4)n(OCF.sub.2)nCF.sub.2CH.sub.2OC.sub.3H.sub.6SC.sub.3H.sub.6Si(OCH-
.sub.3).sub.3 is about 50.degree. C. lower than that for
ECC-1000.TM. with a similar perfluoropolyether backbone but with a
carboxamido linking group.
TABLE-US-00001 TABLE 1 Required CVD Vaporization Temperature for
Silanes Vaporization Silane: Linkage group: Temperature (.degree.
C.): Example 1 Mercapto --S-- 415 Example 2 Mercapto --S-- 415
Example 3 Mercapto --S-- 415 Example 4 Mercapto --S-- 415 Example 5
Mercapto --S-- 415 ECC1000 Carboxamido --CONH-- 475
Drain Time Test:
For this test the drain time of a liquid from a treated ophthalmic
lens was determined using a dip coater. The treated lenses are
dipped into and subsequently withdrawn from a liquid (either oleic
acid or isopropanol (IPA)). The withdrawal speed for the test was 5
cm (2 inches) per second. The time needed for the liquid to drain
completely was measured with a timer.
Table 2 summarizes the measured drain times for the CVD and dip
coated polycarbonate lenses for isopropanol and oleic acid.
According to the data, in general, the CVD coating of the lenses
resulted in shorter drain times for both IPA and oleic acid than
the dip coating. The data also indicate that independent of the
coating method, the silanes with a mercapto linking group result in
shorter drain times than carboxamido linking group even when they
have similar fluorochemical chain (Example 3 vs.
ECC-1000.sup.FTM).
TABLE-US-00002 TABLE 2 Drain time data for various silane
treatments Oleic Acid Isopropanol Drain Time Drain Time Silane:
Coating Method: (seconds): (seconds): Example 1 CVD 12 3 Example 1
Dip Coat 13 4 Example 2 CVD 11 4 Example 2 Dip Coat 14 5 Example 3
CVD 11 3 Example 3 Dip Coat 10 4 Example 4 CVD 19 14 Example 4 Dip
Coat 17 18 Example 5 CVD 34 10 Example 5 Dip Coat 17 4 ECC1000 CVD
15 9 ECC1000 Dip Coat 13 9 Crizal .TM. CVD 26 15 Alize .TM. CVD 10
3 Comparative A Dip Coat 12 3 Comparative B Dip Coat 21 41
Crizal.TM., Obtained from Essilor International, St. Petersburg,
Fla. Alize.TM., Obtained from Essilor International, St.
Petersburg, Fla.
The silane of Comparative A has a formula of
C.sub.3F.sub.7O[CF(CF.sub.3)CF.sub.2O].sub.nCF(CF.sub.3)CONHC.sub.3H.sub.-
6Si(OCH.sub.3).sub.3 The silane of Comparative B is similar to the
silane of Example 4 but is carboxamidosilane.
Static and Dynamic Contact Angles:
The static, advancing and receding contact angle test provides a
quick and precise prediction of the surface properties of coating
materials.
The contact angles for treated lenses (after drying and curing)
were measured using a Kruss G120 and AST VCA 2500 XE Video Contact
Angle System (AST Products, Inc.), both equipped with a computer
for control and date process. The data was generated for both water
and n-hexadecane. Table 3 summarizes the static, advancing and
receding contact angles for lenses treated with various silanes
using both CVD and dip coating processes. Measured contact angles
were high for all treated lenses, although, in general, the lenses
treated by dip coating resulted in slightly higher contact angles.
It was notable that the contact angles for CVD coated lenses were
very close to those for the dip coated lenses which indicated that
the CVD coating were successfully applied.
TABLE-US-00003 TABLE 3 Contact angle data for various silane
treatments Static Advancing Receding Coating Contact Angle Contact
Angle Contact Angle Silane: Method: Water Hexadecane Water
Hexadecane Water Hexadecane Example 1 CVD 114 70 117 72 81 62
Example 1 Dip Coat 117 78 121 79 109 68 Example 2 CVD 104 65 107 68
65 54 Example 2 Dip Coat 115 72 121 77 95 63 Example 3 CVD 107 65
110 67 81 57 Example 3 Dip Coat 109 67 112 69 83 64 Example 4 CVD
109 66 114 68 80 56 Example 4 Dip Coat 107 93 112 67 71 50 Example
5 CVD 98 60 101 61 72 47 Example 5 Dip Coat 115 73 122 75 85 61
Crizal .TM. CVD 118 77 127 78 91 57 Alize .TM. CVD 108 65 110 67 89
58 ECC-1000 CVD 108 65 111 70 68 54 ECC-1000 Dip Coat 116 73 123 72
94 60 Comp. A Dip Coat 123 78 105.5 67 100 67 Comp. B Dip Coat
116.5 68 77.5 59.5 77 61
Hysteresis of Treated Lenses:
The difference between the maximum (advancing) and minimum
(receding) contact angle values is called the contact angle
hysteresis. A great deal of research has gone into analysis of the
significance of hysteresis: it has been used to help characterize
surface heterogeneity, roughness and mobility. Briefly, for
surfaces which are not homogeneous, there are domains on the
surface which present barriers to the motion of the contact line.
In case of chemical heterogeneity these domains represent areas
with different contact angles than the surrounding surface. For
example when wetting with water, hydrophobic domains will pin the
motion of the contact line as the liquid advances thus increasing
the contact angles. When the water recedes the hydrophilic domains
will hold back the draining motion of the contact line thus
decreasing the contact angle. It is possible that the easy cleaning
performance of a coated surface is correlated to the contact angle
hysteresis. The smaller the contact angle hysteresis, the better
the performance. The Table 4 lists the hysteresis of several
treated lenses.
TABLE-US-00004 TABLE 4 Contact angle hysteresis for various silanes
Coating Hysteresis Hysteresis Silane: Method: Water: Hexadecane:
Crizal CVD 36 21 Alize CVD 21 9 1 CVD 35 10 1 dip coat 13 11 2 CVD
42 13 2 dip coat 26 14 3 CVD 28 10 3 dip coat 29 5 ECC-1000 CVD 42
16 ECC-1000 dip coat 28 12 4 CVD 34 11 4 dip coat 41 17 5 CVD 29 14
5 dip coat 37 15
Durability Test:
The durability silane treatments on lenses were determined in the
following manner: The treated lenses were subjected to an abrasion
test using a Lens Eraser Abrasion Tester (obtained from Colts
Laboratories, Inc., Clearwater, Fla.) and a 3M High Performance
Cloth (Scotch-Brite.TM. Microfiber Dusting Cloth, obtained from 3M
Company, St. Paul, Minn.) under a 2.27 kg (5 lbs.) load for 500
cycles. Then the contact angles for the treated lenses following
the abrasion test were measured again using the method described
above. Table 5 shows the contact angle data of the treated lenses
after the abrasion resistance test. A comparison of the contact
angle data for Example 3 before (Table 3) and after (Table 5) the
abrasion test indicated that the Example 3 material had excellent
durability.
TABLE-US-00005 TABLE 5 Contact angle data for various silane
treatments after abrasion test Advancing Receding Coating Contact
Angle Contact Angle Silane: Method: Water Hexadecane Water
Hexadecane Example 1 CVD 98 46 58 35 Example 1 Dip Coat 104 60 64
43 Example 2 CVD 87 -- 47 9 Example 2 Dip Coat 93 52 49 25 Example
3 CVD 107 63 68 47 Example 3 Dip Coat 108 70 84 60 Example 4 CVD 90
55 59 36 Example 4 Dip Coat 96 70 57 41 Example 5 CVD 80 46 47 27
Example 5 Dip Coat 108 86 71 60 Crizal CVD 89 33 40 19 Alize CVD
107 56 69 42 ECC-1000 CVD 111 68 79 56 ECC-1000 Dip Coat 120 64 82
56 Comp. A Dip Coat 97 55.5 55 34 Comp. B Dip Coat 95 48 60
32.3
Adhesion and Edging Testing:
This test is run to determine the ability of a pad to hold a lens
in position in the edger during the cutting operation. Sealing
paper from one side of the Leap Pad III (obtained from 3M Company,
St. Paul, Minn.) was peeled and applied to the center of the coated
lens, which is firmly affixed in the torque tool with 30 cm
(121/4'') bar. A block, the device that holds the lens in position
while the lens rotates, was applied to the other side of the Leap
Pad III. The torque tool with pad and lens was inserted into the
edger (alignment of block flanges into blocker is critical) and
firmly pressed with 2.86 atmospheres (42 psi) pressure on the pad.
The tip of the torque tool was lined up with zero degree on the
torque scale, and a horizontal force of 0.45 kilogram (6 lbs) was
applied using spring scale for one minute and the new position of
torque tool on the torque scale was recorded as the degree from the
zero position. If the torque degree is less than or equal to 5, it
is considered to have adequate adhesion and ability to hold the
lens in the edging process. The test results for the silane
treatments of this invention along with Alize are shown in the
Table 6. The torque degree for Alize lens was >15, which
requires a special temporary coating for the edging process. The
new silane treatments described in this invention all pass this
torque test (<5) except for Example 3, which had the torque
degree of 8. If the CVD coated lens of Example 3 was first washed
with isopropanol before the torque test, the adhesion was improved
and passed the test. Therefore, the silane treatments of this
invention do not require a special temporary coating for the edging
process.
TABLE-US-00006 TABLE 6 Summary of adhesion and edge test data for
silane treatments: Torque Degree Torque Degree Example before IPA
wash after IPA wash 1 4 2 4 3 8 4 4 3 5 4 Alize >15
* * * * *